Answer:
To simplify the expression 5x * 3x, you can multiply the coefficients (numbers) together and then multiply the variables together.
The coefficient of 5x is 5, and the coefficient of 3x is 3. Multiplying them gives us 5 * 3 = 15.
The variable x is being multiplied by x, so we can combine the variables by adding their exponents. The exponent of x is 1, and when multiplied by x (which has an exponent of 1), we get x^1 * x^1 = x^(1+1) = x^2.
Putting it all together, 5x * 3x simplifies to 15x^2.